The present invention relates to angioplasty apparatus for providing a dilation catheter to facilitate a quick exchange of the dilation catheter.
The dilation catheter is introduced into a body of a patient to enlarge constrictions in blood vessels and other body cavities. In one of conventional dilation catheters, an inner lumen is situated inside an outer lumen, and a balloon is attached to the distal end of the outer lumen. A guide wire is located inside the inner lumen.
In this method, firstly, a guide wire is introduced into a desired location, and secondly, the inner lumen with the outer lumen over the guide wire is pushed over the introduced guide wire to the desired location. The inner and outer lumens may be introduced into a blood vessel together with the guide wire.
However, should the need to exchange the introduced catheter, for example to change the size of the balloon, the guide wire must be protruded from the patient's body by a length greater than the length of the dilation catheter. Therefore, an extension wire is attached to the first introduced guide wire. When the catheter is changed, the guide wire is held firm in location, the dilation catheter in the blood vessel is withdrawn, and the new dilation catheter is introduced over the guide wire to complete the exchange. The handling of the extended guide wire is very cumbersome because of the length of the guide wire.
In order to solve the above problem, a short inner lumen is attached to a long outer lumen to extend from the distal end of the outer lumen. The proximal end of the inner lumen is sealingly attached to a side wall of the outer lumen near the distal end thereof. An inflatable balloon is attached between the distal ends of the inner and outer lumens. The guide wire passes through the inner lumen to advance or retract the catheter on the guide wire. The outer lumen has a port on the proximal end, and the balloon is capable of being inflated or deflated through the outer lumen from the proximal end by means of a syringe or other devices.
In the above improved catheter, since the guide wire passes only through the short inner lumen, the catheter can be exchanged easily without using the extension guide wire.
In U.S. Pat. No. 4,762,129, a short tube for guiding the guide wire is attached to the distal end of a long tube. A balloon is also attached to the distal end of the long tube, and a fluid is introduced into the balloon through the long tube.
Although these improved systems mentioned above may avoid the requirements for using the long extended guide wires, the coaxial and dual lumens are attached to the proximal end of the balloon, so that the outer diameter becomes larger as well as the distal end of the catheter is too stiff to follow the bending vessels. Further, in the dual lumen design where the short tube is attached to the long tube, the rotation and pushability of the dilation catheter are reduced since the inner lumen tracking on the guide wire is pushed with the outer lumen in the offset position.
The same can be said on the coaxial design, since the outer lumen does not extend to the distal end of the balloon. Namely, the only common junction between the outer and inner lumens is the one where the proximal end of the inner lumen is exiting from the outer lumen.
In the angioplastisy, the above lumens are generally guided by a guide catheter, and as the blood vessel becomes a small diameter, the lumens are extended from the guide catheter. Thus, the design of the two lumen catheters with the guide wire exiting from the guide catheter increases the outer diameter of the guide catheter or the total size of the dilation catheter to thereby limit the ability of the introduction of two or more of the dilation catheters in the same guide catheter of a small size.
Accordingly, an object of the invention is to provide a dilation catheter to obviate the foregoing difficulties.
Another object of the invention is to provide a dilation catheter as stated above, which has a small diameter and can be controlled easily without trouble.
A further object of the invention is to provide a dilation catheter as stated above, which can be easily manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.